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* powerpc/book3s: Fix CFAR clobbering issue in machine check handler.Mahesh Salgaonkar2014-03-241-0/+8
| | | | | | | | While checking powersaving mode in machine check handler at 0x200, we clobber CFAR register. Fix it by saving and restoring it during beq/bgt. Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* Merge branch 'merge' into nextBenjamin Herrenschmidt2013-12-301-1/+1
|\ | | | | | | | | | | | | Merge a pile of fixes that went into the "merge" branch (3.13-rc's) such as Anton Little Endian fixes. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
| * powerpc: Fix bad stack check in exception entryMichael Neuling2013-12-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In EXCEPTION_PROLOG_COMMON() we check to see if the stack pointer (r1) is valid when coming from the kernel. If it's not valid, we die but with a nice oops message. Currently we allocate a stack frame (subtract INT_FRAME_SIZE) before we check to see if the stack pointer is negative. Unfortunately, this won't detect a bad stack where r1 is less than INT_FRAME_SIZE. This patch fixes the check to compare the modified r1 with -INT_FRAME_SIZE. With this, bad kernel stack pointers (including NULL pointers) are correctly detected again. Kudos to Paulus for finding this. Signed-off-by: Michael Neuling <mikey@neuling.org> cc: stable@vger.kernel.org Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* | powerpc/book3s: Split the common exception prolog logic into two section.Mahesh Salgaonkar2013-12-051-7/+14
|/ | | | | | | | | | | | | | | | | | | | | This patch splits the common exception prolog logic into three parts to facilitate reuse of existing code in the next patch. This patch also re-arranges few instructions in such a way that the second part now deals with saving register values from paca save area to stack frame, and the third part deals with saving current register values to stack frame. The second and third part will be reused in the machine check exception routine in the subsequent patch. Please note that this patch does not introduce or change existing code logic. Instead it is just a code movement and instruction re-ordering. Patch Acked-by Paul. But made some minor modification (explained above) to address Paul's comment in the later patch(3). Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Acked-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* kvm: powerpc: book3s: Cleanup interrupt handling codeAneesh Kumar K.V2013-10-171-0/+11
| | | | | | | | | | With this patch if HV is included, interrupts come in to the HV version of the kvmppc_interrupt code, which then jumps to the PR handler, renamed to kvmppc_interrupt_pr, if the guest is a PR guest. This helps in enabling both HV and PR, which we do in later patch Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Alexander Graf <agraf@suse.de>
* kvm: powerpc: book3s: pr: Rename KVM_BOOK3S_PR to KVM_BOOK3S_PR_POSSIBLEAneesh Kumar K.V2013-10-171-1/+1
| | | | | | | | | With later patches supporting PR kvm as a kernel module, the changes that has to be built into the main kernel binary to enable PR KVM module is now selected via KVM_BOOK3S_PR_POSSIBLE Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Alexander Graf <agraf@suse.de>
* KVM: PPC: Book3S HV: Add support for guest Program Priority RegisterPaul Mackerras2013-10-171-0/+8
| | | | | | | | | | | | | | | | | | | | | | | POWER7 and later IBM server processors have a register called the Program Priority Register (PPR), which controls the priority of each hardware CPU SMT thread, and affects how fast it runs compared to other SMT threads. This priority can be controlled by writing to the PPR or by use of a set of instructions of the form or rN,rN,rN which are otherwise no-ops but have been defined to set the priority to particular levels. This adds code to context switch the PPR when entering and exiting guests and to make the PPR value accessible through the SET/GET_ONE_REG interface. When entering the guest, we set the PPR as late as possible, because if we are setting a low thread priority it will make the code run slowly from that point on. Similarly, the first-level interrupt handlers save the PPR value in the PACA very early on, and set the thread priority to the medium level, so that the interrupt handling code runs at a reasonable speed. Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
* powerpc: Avoid link stack corruption for MMU on exceptionsMichael Neuling2013-08-141-16/+17
| | | | | | | | | | | | | | | | | | | | | | | | | When we have MMU on exceptions (POWER8) and a relocatable kernel, we need to branch from the initial exception vectors at 0x0 to up high where the kernel might be located. Currently we do this using the link register. Unfortunately this corrupts the link stack and instead we should use the count register. We did this for the syscall entry path in: 6a40480 powerpc: Avoid link stack corruption in MMU on syscall entry path but I stupidly forgot to do the same for other exceptions. This patch changes the initial exception vectors to use the count register instead of the link register when we need to branch up to the relocated kernel. I have a dodgy userspace test which loops calling a function that reads the PVR (mfpvr in userspace will be emulated by the kernel via the program check exception). On POWER8 and with CONFIG_RELOCATABLE=y, I get a ~10% performance improvement with my userspace test with this patch. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc/ppc64: Rename SOFT_DISABLE_INTS with RECONCILE_IRQ_STATETiejun Chen2013-08-141-1/+1
| | | | | | | | | The SOFT_DISABLE_INTS seems an odd name for something that updates the software state to be consistent with interrupts being hard disabled, so rename SOFT_DISABLE_INTS with RECONCILE_IRQ_STATE to avoid this confusion. Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* Merge tag 'v3.10' into nextBenjamin Herrenschmidt2013-07-011-1/+1
|\ | | | | | | | | | | Merge 3.10 in order to get some of the last minute powerpc changes, resolve conflicts and add additional fixes on top of them.
| * powerpc: Fix stack overflow crash in resume_kernel when ftracingMichael Ellerman2013-06-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's possible for us to crash when running with ftrace enabled, eg: Bad kernel stack pointer bffffd12 at c00000000000a454 cpu 0x3: Vector: 300 (Data Access) at [c00000000ffe3d40] pc: c00000000000a454: resume_kernel+0x34/0x60 lr: c00000000000335c: performance_monitor_common+0x15c/0x180 sp: bffffd12 msr: 8000000000001032 dar: bffffd12 dsisr: 42000000 If we look at current's stack (paca->__current->stack) we see it is equal to c0000002ecab0000. Our stack is 16K, and comparing to paca->kstack (c0000002ecab3e30) we can see that we have overflowed our kernel stack. This leads to us writing over our struct thread_info, and in this case we have corrupted thread_info->flags and set _TIF_EMULATE_STACK_STORE. Dumping the stack we see: 3:mon> t c0000002ecab0000 [c0000002ecab0000] c00000000002131c .performance_monitor_exception+0x5c/0x70 [c0000002ecab0080] c00000000000335c performance_monitor_common+0x15c/0x180 --- Exception: f01 (Performance Monitor) at c0000000000fb2ec .trace_hardirqs_off+0x1c/0x30 [c0000002ecab0370] c00000000016fdb0 .trace_graph_entry+0xb0/0x280 (unreliable) [c0000002ecab0410] c00000000003d038 .prepare_ftrace_return+0x98/0x130 [c0000002ecab04b0] c00000000000a920 .ftrace_graph_caller+0x14/0x28 [c0000002ecab0520] c0000000000d6b58 .idle_cpu+0x18/0x90 [c0000002ecab05a0] c00000000000a934 .return_to_handler+0x0/0x34 [c0000002ecab0620] c00000000001e660 .timer_interrupt+0x160/0x300 [c0000002ecab06d0] c0000000000025dc decrementer_common+0x15c/0x180 --- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0 [c0000002ecab09c0] c0000000000fe044 .trace_hardirqs_on+0x14/0x30 (unreliable) [c0000002ecab0fb0] c00000000016fe3c .trace_graph_entry+0x13c/0x280 [c0000002ecab1050] c00000000003d038 .prepare_ftrace_return+0x98/0x130 [c0000002ecab10f0] c00000000000a920 .ftrace_graph_caller+0x14/0x28 [c0000002ecab1160] c0000000000161f0 .__ppc64_runlatch_on+0x10/0x40 [c0000002ecab11d0] c00000000000a934 .return_to_handler+0x0/0x34 --- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0 ... and so on __ppc64_runlatch_on() is called from RUNLATCH_ON in the exception entry path. At that point the irq state is not consistent, ie. interrupts are hard disabled (by the exception entry), but the paca soft-enabled flag may be out of sync. This leads to the local_irq_restore() in trace_graph_entry() actually enabling interrupts, which we do not want. Because we have not yet reprogrammed the decrementer we immediately take another decrementer exception, and recurse. The fix is twofold. Firstly make sure we call DISABLE_INTS before calling RUNLATCH_ON. The badly named DISABLE_INTS actually reconciles the irq state in the paca with the hardware, making it safe again to call local_irq_save/restore(). Although that should be sufficient to fix the bug, we also mark the runlatch routines as notrace. They are called very early in the exception entry and we are asking for trouble tracing them. They are also fairly uninteresting and tracing them just adds unnecessary overhead. [ This regression was introduced by fe1952fc0afb9a2e4c79f103c08aef5d13db1873 "powerpc: Rework runlatch code" by myself --BenH ] CC: <stable@vger.kernel.org> [v3.4+] Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* | powerpc: Remove KVMTEST from RELON exception handlersMichael Ellerman2013-07-011-4/+4
|/ | | | | | | | | | | | | | | | | | | KVMTEST is a macro which checks whether we are taking an exception from guest context, if so we branch out of line and eventually call into the KVM code to handle the switch. When running real guests on bare metal (HV KVM) the hardware ensures that we never take a relocation on exception when transitioning from guest to host. For PR KVM we disable relocation on exceptions ourself in kvmppc_core_init_vm(), as of commit a413f47 "Disable relocation on exceptions whenever PR KVM is active". So convert all the RELON macros to use NOTEST, and drop the remaining KVM_HANDLER() definitions we have for 0xe40 and 0xe80. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> CC: <stable@vger.kernel.org> [v3.9+] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Fix "attempt to move .org backwards" errorPaul Mackerras2013-04-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Building a 64-bit powerpc kernel with PR KVM enabled currently gives this error: AS arch/powerpc/kernel/head_64.o arch/powerpc/kernel/exceptions-64s.S: Assembler messages: arch/powerpc/kernel/exceptions-64s.S:258: Error: attempt to move .org backwards make[2]: *** [arch/powerpc/kernel/head_64.o] Error 1 This happens because the MASKABLE_EXCEPTION_PSERIES macro turns into 33 instructions, but we only have space for 32 at the decrementer interrupt vector (from 0x900 to 0x980). In the code generated by the MASKABLE_EXCEPTION_PSERIES macro, we currently have two instances of the HMT_MEDIUM macro, which has the effect of setting the SMT thread priority to medium. One is the first instruction, and is overwritten by a no-op on processors where we save the PPR (processor priority register), that is, POWER7 or later. The other is after we have saved the PPR. In order to reduce the code at 0x900 by one instruction, we omit the first HMT_MEDIUM. On processors without SMT this will have no effect since HMT_MEDIUM is a no-op there. On POWER5 and RS64 machines this will mean that the first few instructions take a little longer in the case where a decrementer interrupt occurs when the hardware thread is running at low SMT priority. On POWER6 and later machines, the hardware automatically boosts the thread priority when a decrementer interrupt is taken if the thread priority was below medium, so this change won't make any difference. The alternative would be to branch out of line after saving the CFAR. However, that would incur an extra overhead on all processors, whereas the approach adopted here only adds overhead on older threaded processors. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc/kvm/book3s_hv: Preserve guest CFAR register valuePaul Mackerras2013-02-151-2/+6
| | | | | | | | | | | | | | | The CFAR (Come-From Address Register) is a useful debugging aid that exists on POWER7 processors. Currently HV KVM doesn't save or restore the CFAR register for guest vcpus, making the CFAR of limited use in guests. This adds the necessary code to capture the CFAR value saved in the early exception entry code (it has to be saved before any branch is executed), save it in the vcpu.arch struct, and restore it on entry to the guest. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Save CFAR before branching in interrupt entry pathsPaul Mackerras2013-02-151-16/+68
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some of the interrupt vectors on 64-bit POWER server processors are only 32 bytes long, which is not enough for the full first-level interrupt handler. For these we currently just have a branch to an out-of-line handler. However, this means that we corrupt the CFAR (come-from address register) on POWER7 and later processors. To fix this, we split the EXCEPTION_PROLOG_1 macro into two pieces: EXCEPTION_PROLOG_0 contains the part up to the point where the CFAR is saved in the PACA, and EXCEPTION_PROLOG_1 contains the rest. We then put EXCEPTION_PROLOG_0 in the short interrupt vectors before we branch to the out-of-line handler, which contains the rest of the first-level interrupt handler. To facilitate this, we define new _OOL (out of line) variants of STD_EXCEPTION_PSERIES, etc. In order to get EXCEPTION_PROLOG_0 to be short enough, i.e., no more than 6 instructions, it was necessary to move the stores that move the PPR and CFAR values into the PACA into __EXCEPTION_PROLOG_1 and to get rid of one of the two HMT_MEDIUM instructions. Previously there was a HMT_MEDIUM_PPR_DISCARD before the prolog, which was nop'd out on processors with the PPR (POWER7 and later), and then another HMT_MEDIUM inside the HMT_MEDIUM_PPR_SAVE macro call inside __EXCEPTION_PROLOG_1, which was nop'd out on processors without PPR. Now the HMT_MEDIUM inside EXCEPTION_PROLOG_0 is there unconditionally and the HMT_MEDIUM_PPR_DISCARD is not strictly necessary, although this leaves it in for the interrupt vectors where there is room for it. Previously we had a handler for hypervisor maintenance interrupts at 0xe50, which doesn't leave enough room for the vector for hypervisor emulation assist interrupts at 0xe40, since we need 8 instructions. The 0xe50 vector was only used on POWER6, as the HMI vector was moved to 0xe60 on POWER7. Since we don't support running in hypervisor mode on POWER6, we just remove the handler at 0xe50. This also changes denorm_exception_hv to use EXCEPTION_PROLOG_0 instead of open-coding it, and removes the HMT_MEDIUM_PPR_DISCARD from the relocation-on vectors (since any CPU that supports relocation-on interrupts also has the PPR). Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Implement PPR save/restoreHaren Myneni2013-01-101-8/+10
| | | | | | | | | | | | | | | | | | | | | | | [PATCH 6/6] powerpc: Implement PPR save/restore When the task enters in to kernel space, the user defined priority (PPR) will be saved in to PACA at the beginning of first level exception vector and then copy from PACA to thread_info in second level vector. PPR will be restored from thread_info before exits the kernel space. P7/P8 temporarily raises the thread priority to higher level during exception until the program executes HMT_* calls. But it will not modify PPR register. So we save PPR value whenever some register is available to use and then calls HMT_MEDIUM to increase the priority. This feature supports on P7 or later processors. We save/ restore PPR for all exception vectors except system call entry. GLIBC will be saving / restore for system calls. So the default PPR value (3) will be set for the system call exit when the task returned to the user space. Signed-off-by: Haren Myneni <haren@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Macros for saving/restore PPRHaren Myneni2013-01-101-0/+37
| | | | | | | | | [PATCH 5/6] powerpc: Macros for saving/restore PPR Several macros are defined for saving and restore user defined PPR value. Signed-off-by: Haren Myneni <haren@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Increase exceptions arrays in paca struct to save PPRHaren Myneni2013-01-101-0/+1
| | | | | | | | | [PATCH 3/6] powerpc: Increase exceptions arrays in paca struct to save PPR Using paca to save user defined PPR value in the first level exception vector. Signed-off-by: Haren Myneni <haren@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to callerHaren Myneni2013-01-101-1/+2
| | | | | | | | | | | | [PATCH 1/6] powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to caller The first instruction in ACCOUNT_CPU_USER_ENTRY is 'beq' which checks for exceptions coming from kernel mode. PPR value will be saved immediately after ACCOUNT_CPU_USER_ENTRY and is also for user level exceptions. So moved this branch instruction in the caller code. Signed-off-by: Haren Myneni <haren@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Add book3s privileged doorbell exception vectorsIan Munsie2013-01-101-0/+1
| | | | | | | | | | | | | Directed Privileged Doorbell Interrupts come in at 0xa00 (or 0xc000000000004a00 if relocation on exception is enabled), so add exception vectors at these locations. If doorbell support is not compiled in we handle it as an unknown_exception. Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Tested-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Add book3s hypervisor doorbell exception vectorsIan Munsie2013-01-101-0/+2
| | | | | | | | | | | | | Directed Hypervisor Doorbell Interrupts come in at 0xe80 (or 0xc000000000004e80 if relocation on exceptions is enabled), so add exception vectors at these locations. If doorbell support is not compiled in we handle it as an unknown_exception. Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Tested-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Add relocation on exception vector handlersMichael Neuling2012-11-151-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | POWER8/v2.07 allows exceptions to be taken with the MMU still on. A new set of exception vectors is added at 0xc000_0000_0000_4xxx. When the HW takes us here, MSR IR/DR will be set already and we no longer need a costly RFID to turn the MMU back on again. The original 0x0 based exception vectors remain for when the HW can't leave the MMU on. Examples of this are when we can't trust the current MMU mappings, like when we are changing from guest to hypervisor (HV 0 -> 1) or when the MMU was off already. In these cases the HW will take us to the original 0x0 based exception vectors with the MMU off as before. This uses the new macros added previously too implement these new execption vectors at 0xc000_0000_0000_4xxx. We exit these exception vectors using mflr/blr (rather than mtspr SSR0/RFID), since we don't need the costly MMU switch anymore. This moves the __end_interrupts marker down past these new 0x4000 vectors since they will need to be copied down to 0x0 when the kernel is not at 0x0. Signed-off-by: Matt Evans <matt@ozlabs.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Add new macros needed for relocation on exceptionsMichael Neuling2012-11-151-0/+90
| | | | | | | | | | | | | | | | | | | | | | | POWER8/v2.07 allows exceptions to be taken with the MMU still on. A new set of exception vectors is added at 0xc000_0000_0000_4xxx. When the HW takes us here, MSR IR/DR will be set already and we no longer need a costly RFID to turn the MMU back on again. The original 0x0 based exception vectors remain for when the HW can't leave the MMU on. Examples of this are when we can't trust the current the MMU mappings, like when we are changing from guest to hypervisor (HV 0 -> 1) or when the MMU was off already. In these cases the HW will take us to the original 0x0 based exception vectors with the MMU off as before. The below macros are copies of the macros used at the 0x0 offset but modified to handle the MMU being on. In these macros we use the link register to jump to the secondary handlers rather than using RFID (RFID was also use to turn on the MMU). Signed-off-by: Matt Evans <matt@ozlabs.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Make load_hander handle upto 64k offsetMichael Neuling2012-11-151-1/+2
| | | | | | | If we change load_hander() to use an ori instead of addi, we can load handlers upto 64k away provided we are still 64k aligned. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Use CURRENT_THREAD_INFO instead of open coded assemblyStuart Yoder2012-07-111-2/+2
| | | | | Signed-off-by: Stuart Yoder <stuart.yoder@freescale.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc/irq: Make alignment & program interrupt behave the sameBenjamin Herrenschmidt2012-05-091-7/+0
| | | | | | | | | | Alignment was the last user of the ENABLE_INTS macro, which we can now remove. All non-syscall exceptions now disable interrupts on entry, they get re-enabled conditionally from C code. Don't unconditionally re-enable in program check either, check the original context. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Rework lazy-interrupt handlingBenjamin Herrenschmidt2012-03-091-21/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current implementation of lazy interrupts handling has some issues that this tries to address. We don't do the various workarounds we need to do when re-enabling interrupts in some cases such as when returning from an interrupt and thus we may still lose or get delayed decrementer or doorbell interrupts. The current scheme also makes it much harder to handle the external "edge" interrupts provided by some BookE processors when using the EPR facility (External Proxy) and the Freescale Hypervisor. Additionally, we tend to keep interrupts hard disabled in a number of cases, such as decrementer interrupts, external interrupts, or when a masked decrementer interrupt is pending. This is sub-optimal. This is an attempt at fixing it all in one go by reworking the way we do the lazy interrupt disabling from the ground up. The base idea is to replace the "hard_enabled" field with a "irq_happened" field in which we store a bit mask of what interrupt occurred while soft-disabled. When re-enabling, either via arch_local_irq_restore() or when returning from an interrupt, we can now decide what to do by testing bits in that field. We then implement replaying of the missed interrupts either by re-using the existing exception frame (in exception exit case) or via the creation of a new one from an assembly trampoline (in the arch_local_irq_enable case). This removes the need to play with the decrementer to try to create fake interrupts, among others. In addition, this adds a few refinements: - We no longer hard disable decrementer interrupts that occur while soft-disabled. We now simply bump the decrementer back to max (on BookS) or leave it stopped (on BookE) and continue with hard interrupts enabled, which means that we'll potentially get better sample quality from performance monitor interrupts. - Timer, decrementer and doorbell interrupts now hard-enable shortly after removing the source of the interrupt, which means they no longer run entirely hard disabled. Again, this will improve perf sample quality. - On Book3E 64-bit, we now make the performance monitor interrupt act as an NMI like Book3S (the necessary C code for that to work appear to already be present in the FSL perf code, notably calling nmi_enter instead of irq_enter). (This also fixes a bug where BookE perfmon interrupts could clobber r14 ... oops) - We could make "masked" decrementer interrupts act as NMIs when doing timer-based perf sampling to improve the sample quality. Signed-off-by-yet: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- v2: - Add hard-enable to decrementer, timer and doorbells - Fix CR clobber in masked irq handling on BookE - Make embedded perf interrupt act as an NMI - Add a PACA_HAPPENED_EE_EDGE for use by FSL if they want to retrigger an interrupt without preventing hard-enable v3: - Fix or vs. ori bug on Book3E - Fix enabling of interrupts for some exceptions on Book3E v4: - Fix resend of doorbells on return from interrupt on Book3E v5: - Rebased on top of my latest series, which involves some significant rework of some aspects of the patch. v6: - 32-bit compile fix - more compile fixes with various .config combos - factor out the asm code to soft-disable interrupts - remove the C wrapper around preempt_schedule_irq v7: - Fix a bug with hard irq state tracking on native power7
* powerpc: Replace mfmsr instructions with load from PACA kernel_msr fieldBenjamin Herrenschmidt2012-03-091-1/+1
| | | | | | | | On 64-bit, the mfmsr instruction can be quite slow, slower than loading a field from the cache-hot PACA, which happens to already contain the value we want in most cases. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Improve behaviour of irq tracing on 64-bit exception entryBenjamin Herrenschmidt2012-03-091-3/+22
| | | | | | | | | | | | | | | Some exceptions would unconditionally disable interrupts on entry, which is fine, but calling lockdep every time not only adds more overhead than strictly needed, but also means we get quite a few "redudant" disable logged, which makes it hard to spot the really bad ones. So instead, split the macro used by the exception code into a normal one and a separate one used when CONFIG_TRACE_IRQFLAGS is enabled, and make the later skip th tracing if interrupts were already disabled. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Rework runlatch codeBenjamin Herrenschmidt2012-03-091-23/+27
| | | | | | | | | | | This moves the inlines into system.h and changes the runlatch code to use the thread local flags (non-atomic) rather than the TIF flags (atomic) to keep track of the latch state. The code to turn it back on in an asynchronous interrupt is now simplified and partially inlined. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Use the same interrupt prolog for perfmon as other interruptsBenjamin Herrenschmidt2012-03-091-14/+3
| | | | | | | | | | | | | The perfmon interrupt is the sole user of a special variant of the interrupt prolog which differs from the one used by external and timer interrupts in that it saves the non-volatile GPRs and doesn't turn the runlatch on. The former is unnecessary and the later is arguably incorrect, so let's clean that up by using the same prolog. While at it we rename that prolog to use the _ASYNC prefix. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Remove legacy iSeries bits from assembly filesBenjamin Herrenschmidt2012-03-091-15/+0
| | | | | | | | | This removes the various bits of assembly in the kernel entry, exception handling and SLB management code that were specific to running under the legacy iSeries hypervisor which is no longer supported. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* KVM: PPC: book3s_hv: Add support for PPC970-family processorsPaul Mackerras2011-07-121-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds support for running KVM guests in supervisor mode on those PPC970 processors that have a usable hypervisor mode. Unfortunately, Apple G5 machines have supervisor mode disabled (MSR[HV] is forced to 1), but the YDL PowerStation does have a usable hypervisor mode. There are several differences between the PPC970 and POWER7 in how guests are managed. These differences are accommodated using the CPU_FTR_ARCH_201 (PPC970) and CPU_FTR_ARCH_206 (POWER7) CPU feature bits. Notably, on PPC970: * The LPCR, LPID or RMOR registers don't exist, and the functions of those registers are provided by bits in HID4 and one bit in HID0. * External interrupts can be directed to the hypervisor, but unlike POWER7 they are masked by MSR[EE] in non-hypervisor modes and use SRR0/1 not HSRR0/1. * There is no virtual RMA (VRMA) mode; the guest must use an RMO (real mode offset) area. * The TLB entries are not tagged with the LPID, so it is necessary to flush the whole TLB on partition switch. Furthermore, when switching partitions we have to ensure that no other CPU is executing the tlbie or tlbsync instructions in either the old or the new partition, otherwise undefined behaviour can occur. * The PMU has 8 counters (PMC registers) rather than 6. * The DSCR, PURR, SPURR, AMR, AMOR, UAMOR registers don't exist. * The SLB has 64 entries rather than 32. * There is no mediated external interrupt facility, so if we switch to a guest that has a virtual external interrupt pending but the guest has MSR[EE] = 0, we have to arrange to have an interrupt pending for it so that we can get control back once it re-enables interrupts. We do that by sending ourselves an IPI with smp_send_reschedule after hard-disabling interrupts. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
* KVM: PPC: Add support for Book3S processors in hypervisor modePaul Mackerras2011-07-121-4/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds support for KVM running on 64-bit Book 3S processors, specifically POWER7, in hypervisor mode. Using hypervisor mode means that the guest can use the processor's supervisor mode. That means that the guest can execute privileged instructions and access privileged registers itself without trapping to the host. This gives excellent performance, but does mean that KVM cannot emulate a processor architecture other than the one that the hardware implements. This code assumes that the guest is running paravirtualized using the PAPR (Power Architecture Platform Requirements) interface, which is the interface that IBM's PowerVM hypervisor uses. That means that existing Linux distributions that run on IBM pSeries machines will also run under KVM without modification. In order to communicate the PAPR hypercalls to qemu, this adds a new KVM_EXIT_PAPR_HCALL exit code to include/linux/kvm.h. Currently the choice between book3s_hv support and book3s_pr support (i.e. the existing code, which runs the guest in user mode) has to be made at kernel configuration time, so a given kernel binary can only do one or the other. This new book3s_hv code doesn't support MMIO emulation at present. Since we are running paravirtualized guests, this isn't a serious restriction. With the guest running in supervisor mode, most exceptions go straight to the guest. We will never get data or instruction storage or segment interrupts, alignment interrupts, decrementer interrupts, program interrupts, single-step interrupts, etc., coming to the hypervisor from the guest. Therefore this introduces a new KVMTEST_NONHV macro for the exception entry path so that we don't have to do the KVM test on entry to those exception handlers. We do however get hypervisor decrementer, hypervisor data storage, hypervisor instruction storage, and hypervisor emulation assist interrupts, so we have to handle those. In hypervisor mode, real-mode accesses can access all of RAM, not just a limited amount. Therefore we put all the guest state in the vcpu.arch and use the shadow_vcpu in the PACA only for temporary scratch space. We allocate the vcpu with kzalloc rather than vzalloc, and we don't use anything in the kvmppc_vcpu_book3s struct, so we don't allocate it. We don't have a shared page with the guest, but we still need a kvm_vcpu_arch_shared struct to store the values of various registers, so we include one in the vcpu_arch struct. The POWER7 processor has a restriction that all threads in a core have to be in the same partition. MMU-on kernel code counts as a partition (partition 0), so we have to do a partition switch on every entry to and exit from the guest. At present we require the host and guest to run in single-thread mode because of this hardware restriction. This code allocates a hashed page table for the guest and initializes it with HPTEs for the guest's Virtual Real Memory Area (VRMA). We require that the guest memory is allocated using 16MB huge pages, in order to simplify the low-level memory management. This also means that we can get away without tracking paging activity in the host for now, since huge pages can't be paged or swapped. This also adds a few new exports needed by the book3s_hv code. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
* KVM: PPC: Split host-state fields out of kvmppc_book3s_shadow_vcpuPaul Mackerras2011-07-121-5/+5
| | | | | | | | | | | | | | | | | | | | | | There are several fields in struct kvmppc_book3s_shadow_vcpu that temporarily store bits of host state while a guest is running, rather than anything relating to the particular guest or vcpu. This splits them out into a new kvmppc_host_state structure and modifies the definitions in asm-offsets.c to suit. On 32-bit, we have a kvmppc_host_state structure inside the kvmppc_book3s_shadow_vcpu since the assembly code needs to be able to get to them both with one pointer. On 64-bit they are separate fields in the PACA. This means that on 64-bit we don't need to copy the kvmppc_host_state in and out on vcpu load/unload, and in future will mean that the book3s_hv code doesn't need a shadow_vcpu struct in the PACA at all. That does mean that we have to be careful not to rely on any values persisting in the hstate field of the paca across any point where we could block or get preempted. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
* powerpc, KVM: Rework KVM checks in first-level interrupt handlersPaul Mackerras2011-07-121-40/+81
| | | | | | | | | | | | | | | | | Instead of branching out-of-line with the DO_KVM macro to check if we are in a KVM guest at the time of an interrupt, this moves the KVM check inline in the first-level interrupt handlers. This speeds up the non-KVM case and makes sure that none of the interrupt handlers are missing the check. Because the first-level interrupt handlers are now larger, some things had to be move out of line in exceptions-64s.S. This all necessitated some minor changes to the interrupt entry code in KVM. This also streamlines the book3s_32 KVM test. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
* powerpc: Save Come-From Address Register (CFAR) in exception framePaul Mackerras2011-05-041-0/+9
| | | | | | | | | | | | | | | | | | | | Recent 64-bit server processors (POWER6 and POWER7) have a "Come-From Address Register" (CFAR), that records the address of the most recent branch or rfid (return from interrupt) instruction for debugging purposes. This saves the value of the CFAR in the exception entry code and stores it in the exception frame. We also make xmon print the CFAR value in its register dump code. Rather than extend the pt_regs struct at this time, we steal the orig_gpr3 field, which is only used for system calls, and use it for the CFAR value for all exceptions/interrupts other than system calls. This means we don't save the CFAR on system calls, which is not a great problem since system calls tend not to happen unexpectedly, and also avoids adding the overhead of reading the CFAR to the system call entry path. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Save register r9-r13 values accurately on interrupt with bad stackPaul Mackerras2011-05-041-3/+4
| | | | | | | | | | | | | | | | | | | | When we take an interrupt or exception from kernel mode and the stack pointer is obviously not a kernel address (i.e. the top bit is 0), we switch to an emergency stack, save register values and panic. However, on 64-bit server machines, we don't actually save the values of r9 - r13 at the time of the interrupt, but rather values corrupted by the exception entry code for r12-r13, and nothing at all for r9-r11. This fixes it by passing a pointer to the register save area in the paca through to the bad_stack code in r3. The register values are saved in one of the paca register save areas (depending on which exception this is). Using the pointer in r3, the bad_stack code now retrieves the saved values of r9 - r13 and stores them in the exception frame on the emergency stack. This also stores the normal exception frame marker ("regshere") in the exception frame. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Always use SPRN_SPRG_HSCRATCH0 when running in HV modePaul Mackerras2011-04-201-8/+7
| | | | | | | | | | | | This uses feature sections to arrange that we always use HSPRG1 as the scratch register in the interrupt entry code rather than SPRG2 when we're running in hypervisor mode on POWER7. This will ensure that we don't trash the guest's SPRG2 when we are running KVM guests. To simplify the code, we define GET_SCRATCH0() and SET_SCRATCH0() macros like the GET_PACA/SET_PACA macros. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: More work to support HV exceptionsBenjamin Herrenschmidt2011-04-201-13/+24
| | | | | | | Rework exception macros a bit to split offset from vector and add some basic support for HDEC, HDSI, HISI and a few more. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Base support for exceptions using HSRR0/1Benjamin Herrenschmidt2011-04-201-32/+33
| | | | | | | | | Pass the register type to the prolog, also provides alternate "HV" version of hardware interrupt (0x500) and adjust LPES accordingly We tag those interrupts by setting bit 0x2 in the trap number Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: In HV mode, use HSPRG0 for PACABenjamin Herrenschmidt2011-04-201-3/+3
| | | | | | | | | When running in Hypervisor mode (arch 2.06 or later), we store the PACA in HSPRG0 instead of SPRG1. The architecture specifies that SPRGs may be lost during a "nap" power management operation (though they aren't currently on POWER7) and this enables use of SPRG1 by KVM guests. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Account time using timebase rather than PURRPaul Mackerras2010-09-021-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, when CONFIG_VIRT_CPU_ACCOUNTING is enabled, we use the PURR register for measuring the user and system time used by processes, as well as other related times such as hardirq and softirq times. This turns out to be quite confusing for users because it means that a program will often be measured as taking less time when run on a multi-threaded processor (SMT2 or SMT4 mode) than it does when run on a single-threaded processor (ST mode), even though the program takes longer to finish. The discrepancy is accounted for as stolen time, which is also confusing, particularly when there are no other partitions running. This changes the accounting to use the timebase instead, meaning that the reported user and system times are the actual number of real-time seconds that the program was executing on the processor thread, regardless of which SMT mode the processor is in. Thus a program will generally show greater user and system times when run on a multi-threaded processor than on a single-threaded processor. On pSeries systems on POWER5 or later processors, we measure the stolen time (time when this partition wasn't running) using the hypervisor dispatch trace log. We check for new entries in the log on every entry from user mode and on every transition from kernel process context to soft or hard IRQ context (i.e. when account_system_vtime() gets called). So that we can correctly distinguish time stolen from user time and time stolen from system time, without having to check the log on every exit to user mode, we store separate timestamps for exit to user mode and entry from user mode. On systems that have a SPURR (POWER6 and POWER7), we read the SPURR in account_system_vtime() (as before), and then apportion the SPURR ticks since the last time we read it between scaled user time and scaled system time according to the relative proportions of user time and system time over the same interval. This avoids having to read the SPURR on every kernel entry and exit. On systems that have PURR but not SPURR (i.e., POWER5), we do the same using the PURR rather than the SPURR. This disables the DTL user interface in /sys/debug/kernel/powerpc/dtl for now since it conflicts with the use of the dispatch trace log by the time accounting code. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* Make head_64.S aware of KVM real mode codeAlexander Graf2009-11-051-0/+2
| | | | | | | | | | | | | | We need to run some KVM trampoline code in real mode. Unfortunately, real mode only covers 8MB on Cell so we need to squeeze ourselves as low as possible. Also, we need to trap interrupts to get us back from guest state to host state without telling Linux about it. This patch adds interrupt traps and includes the KVM code that requires real mode in the real mode parts of Linux. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Remove use of a second scratch SPRG in STAB codeBenjamin Herrenschmidt2009-08-201-2/+5
| | | | | | | | | | | | | | | The STAB code used on Power3 and RS/64 uses a second scratch SPRG to save a GPR in order to decide whether to go to do_stab_bolted_* or to handle a normal data access exception. This prevents our scheme of freeing SPRG3 which is user visible for user uses since we cannot use SPRG0 which, on RS/64, seems to be read-only for supervisor mode (like POWER4). This reworks the STAB exception entry to use the PACA as temporary storage instead. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Use names rather than numbers for SPRGs (v2)Benjamin Herrenschmidt2009-08-201-9/+9
| | | | | | | | | | | | | | | | | | | | | | The kernel uses SPRG registers for various purposes, typically in low level assembly code as scratch registers or to hold per-cpu global infos such as the PACA or the current thread_info pointer. We want to be able to easily shuffle the usage of those registers as some implementations have specific constraints realted to some of them, for example, some have userspace readable aliases, etc.. and the current choice isn't always the best. This patch should not change any code generation, and replaces the usage of SPRN_SPRGn everywhere in the kernel with a named replacement and adds documentation next to the definition of the names as to what those are used for on each processor family. The only parts that still use the original numbers are bits of KVM or suspend/resume code that just blindly needs to save/restore all the SPRGs. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* powerpc: Rename exception.h to exception-64s.hBenjamin Herrenschmidt2009-08-201-0/+279
The file include/asm/exception.h contains definitions that are specific to exception handling on 64-bit server type processors. This renames the file to exception-64s.h to reflect that fact and avoid confusion. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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